text:
Are sequenced waypoints still displayed on the Navigation Display / FMS legs page?
This question relates to the Flight Management System of a large airliner, e.g. Boeing 787:
During a flight, when the aircraft passes a waypoint, is this just passed waypoint (and the previous ones) still shown on the legs / FPLN page of the Flight Management System? Asked differently, can I scroll through all the past waypoints or are they automatically deleted once I have passed them?
Does the same apply to the Navigation Display (if I'd zoom out enough), would I still see all already sequenced waypoints and the past route, or do I only get to see the upcoming route and waypoints?
If they are not visible any more, why so?

The B787 is one type of implementation, others could vary. Yes, if you were able to zoom out enough you would see previous WPTs though they are no longer displayed on the active plan 'legs page' of the FMC CDU. Though I've shown the normal ND Map mode display below, there is another mode called Centered Map mode that displays the airplane at the center of a '360deg compass rose' type display with half the selected range in front and half the selected range behind the airplane and the active route displayed for both forward and aft areas.

Map mode with 'from' WPT visible.

.
The FMC/CDU does not keep a history of the flown route, but at any given time, two routes, named RTE 1 and RTE 2 can be stored on the FMC for rapid activation, and one of these, conventionally RTE 1 is activated to become the 'live route'.
So though on the active flown route there's no realtime history, of WPTs passed, instead, the route as originally planned can be viewed on the CDU and ND Plan mode (North UP) by looking at RTE 1.
Your question "If they're not visible now, why so?", could instead be applied to the CDU, in which case the argument against would be:
(a) Having this RTE 1 available for rapid activation in case of a loss of the FMC Route, is the most likely scenario for it's use.
(b) For the en-route diversion scenarios The B787 has other dedicated methods.
(c) This system implementation is more suitable for long range flights  having many possible diversion scenarios. A turnback and diversion back following the route history is unlikely in today's airspace structure and air traffic.


text:
Can I Restrict Commercial air Traffic above My Land for ordinary use and enjoyment?
I have 7.72 acres in the Southern California Desert. It's outside of Palm Springs Ca.
My land was granted to My Grandfather in 1961 as a homestead. The patent states that I have ALL Rights, Privileges, and Immunities entitled by LAW (it also states these things are Forever). I intend to open a Droneport. I am hoping to restrict my airspace from commercial traffic, thus creating an unlimited height for Drones. My intent would be to have high altitude competitions and high altitude test flights. Of course the use would only be permitted within my land boundaries.
Since any New law requires a "savings provision" that state, Any new law in no way infringes on any Patent right, Also known as a "Grandfather Clause"
I believe that My Use would constitute ordinary use and enjoyment of the Land.
I would appreciate any thoughts or feedback.

Welcome to Aviation.SE.  If you don't get any answers here after a few days, you might try posting your question over on our [Law.SE] sister site.

No.  At common law (i.e., the law that existed before the existence of law statutes), there was a doctrine known as ad coelum, literally "to the skies";  it meant that anyone who owned the land controlled it from the skies to the depths.
But in the United States, Congress did away with this doctrine in the Civil Aeronautics Act of 1938.  In this act, they declared that all navigable airspace above the United States was effectively a "public highway", i.e., was no longer private:

There is hereby recognized and declared to exist in behalf of any citizen of the United States public right of freedom of transit in air commerce through the navigable airspace of the United States.

The airspace to which this law applied was carved back a bit by the Supreme Court in United States v. Causby (1946).  The ultimate effect of that decision was that the airspace below a certain level (365 feet) would be under the control of the landowner;  in particular, if flights below this altitude impaired the usefulness of the property, the landowner would be due compensation.  But the court decision explicitly affirmed that the old usque ad coelum doctrine no longer applied:

The common law doctrine that ownership of land extends to the periphery of the universe has no place in the modern world.

Why 365ft? I couldn't see that in the judgement. I can see why the judgement might lead indirectly to 500ft, 1000ft or 2000ft but I can't find anything that would lead to 365ft. (I believe you, I'm just curious).

@DanSheppard:  It appears that number was actually settled upon by a lower court, as the lower limit of what was considered "navigable airspace" at the time.  There are some more details in the Wikipedia article on the case.  (Edited to better reflect this subtlety.)

@DanSheppard Also, my link is to the "syllabus" of the case, which in SCOTUS-speak is effectively an executive summary.  I wasn't able to quickly find the full opinion online, though I'm sure it must be out there somewhere, and it might have more details about the rules surrounding airspace at the time.

In the context of the original question, imagine if every land owner were to determine the navigability of the airspace above their property, or were to charge for passage.  A nightmare situation.  Property ownership does not carry all rights; one can have property, but no water rights, for example.  Airspace overhead does come with stipulations, and minimum altitudes by aircraft, established by the FAA: https://www.ecfr.gov/cgi-bin/text-idx?SID=751bfc2eaf882e9acd0f052d3618e096&mc=true&node=se14.2.91_1119&rgn=div8

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text:
What does the message content in the ARINC 615A FIND protocol look like?
I know the FIND protocol is used to discover which LRUs are available if the data loader supports the FIND protocol.  I also know the message is sent as a broadcast using UDP, but what is in the message that's being broadcasted?

ARINC 615A dataload protocol does not use ARINC 429 (ARINC 615 does). ARINC 615A uses Ethernet.

I did not tag this 429.  I am looking for 615 over Ethernet

Attachment 3 of ARINC 615A-3 describes the FIND function. The FIND protocol has an Information Request (IRQ) packet and an Information Answer (IAN) packet. Each packet contains a 2 byte header and a variable length data portion.

3-4 Information Request Packet
Source MAC address should be the MAC address of the data loader (or
  the initiator.
Destination MAC address should be a unicast, multicast, or the
  broadcast MAC address.
Source IP Address should be the IP address of the Data loader (or the
  initiator).
Destination IP address should be a unicast, multicast, or a broadcast
  IP address (full broadcast i.e., 255.255.255.255 or class-relevant
  broadcast e.g., 220.130.48.255 for a class C).
Opcode value should be IRQ (0x0001).
Data list should be a null ASCII string with terminator: 0x00.
Packet is terminated by 0x10.

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text:
Does an airline have to pay if fighters intercept one of its aircraft?
It sometimes happens that because loss of radio communication or because wrong frequency tuned in during ATC handover etc... a country has to send fighters to intercept an aircraft in its airspace. If such happens, does the airline have to pay a fine (presumably this would/should cover the expenses of the dispatched fighters)? What happens with the pilots who make this mistake?
Let's assume a European country, member of NATO and a commercial flight.
EDIT - 2018-12-17
It looks my country (Hungary) will be the first in the EU which will charge airines (actually based on the Hungarian Official Gazette they can charge anyone not just commercial flights) in this case. The amount itself is not defined, the Aviation Authority will be responsible for determining it (of course along with the military counterparty). Link for the Hungarian Official Gazette - in Hungarian

I’m not aware of any nations that do.  I’d have to say that’s getting pretty stingy on the part of a government to start charging for emergency services or other public goods outside of conventional taxes

Probably not very likely. In 1978 Soviet Union asked US\$100,000 (\$375,200 today) for "caretaking passengers" after their interceptors forced to land KAL 902 on the frozen lake (has never been paid). However firing the two R-60 missiles from interceptors into the airliner was for free.

Given that Korean Airlines is flying to Russian Federation cities on a regular basis, it's more likely that the Russian government rescinded that fee.

The answer depends entirely on the country the aircraft is overflying when an intercept is ordered or requested. I can't imagine payment being demanded by an EU country if the intercept is performed due to a bonafide emergency, or simply out of an excess of caution. However, I know of countries where airport staff will deliberately leave airport runway lights on during the day just to be able to send a bill to the aircraft owner for the service.
That said, I can envision an airline being asked to pay the costs if the situation takes place as a result of pilot incompetence or something similar.

I don't understand this answer. Charge what aircraft owner? If they leave lights on all day and have 100 takeoffs during that time, who pays for these lights? Also, if you say they would indeed receive an invoice, please provide a reference?

Pretty much all aircraft except ultralights are required to display registration numbers. In the country's registry, that tells you who is the registered owner. The owners are charged for whatever services they consume, such as overlight fees, landing fees, etc. The Federal Aviation Administration manages the overflight fees charged to aircraft who overfly the US but neither land nor take off in the country. The system is explained here: https://www.faa.gov/air_traffic/international_aviation/overflight_fees/.

@Cloud: All 100 of them, of course.

@StephenSprunk is right. In some third world countries they'll leave the runway lights on to charge unsuspecting aircraft owners for the service -- in full daylight. They won't turn them off until you yell at them 3 times and threaten to storm the tower yourself and turn them off. LOL! :)

In many developing countries, govt fees are not for cost recovery or to discourage undesirable behavior; gouging foreigners (for as much and as often as possible) is a critical sector of their economy--whether it actually ends up in the treasury or just the collector's pockets.

That is a self-defeating argument. When the pilot doesn't come back after the one-time gouge you have lost any value to the economy, and even more so when word gets around.


text:
How does the bypass air provide thrust?
To my knowledge, bypass air produces 80% of total thrust. But I don't understand to how it does that. By accelerating the air, by increasing the speed or increasing the pressure of the air? Is it doing this by Bernoulli's principle or something like that?

The bypass air is accelerated by the fan at the front of the turbofan engine. This changes its velocity and therefore its momentum, which is the definition of a force (in this case: thrust):
$$ F = \frac{\text{d}}{\text{d}t} p = m \frac{\text{d}}{\text{d}t} v = m \cdot a $$
This thrust contributes to the total thrust of the engine. How much will depend on the bypass ratio of the engine and other parameters, but 80% is plausible for a high bypass turbofan. Bernoulli's principle has nothing to do with this.
You can see the accelerated airflow in the following animation:

(source: Wikimedia)
The air coming from the engine core will move even faster, but there is less of it in a high bypass turbofan resulting in less total thrust coming from the core:

The fan airflow, referred to as the cold air stream, is accelerated by the fan and passes through the engine remaining outside of the engine core. The cold air stream moves much slower than the hot stream gas flow passing through the engine core.

(skybrary.aero)

"The air coming from the engine core will move even faster, but there is less of it in a high bypass turbofan resulting in less total thrust coming from the core" To expand on that: a jet engine's efficiency is (speaking simply) related to the change in velocity of the airstream. The greater the difference in velocity between intake and exhaust, the lower the efficiency (but the greater the thrust). Therefore, it is more efficient (and therefore cheaper) to give a much smaller velocity increase to the air, and use a much larger volume of air so that it adds up to the same overall thrust.

"The bypass air is accelerated by the fan". This statement is not strictly correct. The Fan accelerate air to create and maintain flow, but the acceleration is not great and not in axial direction (which is responsible of thrust). In fact, the main role of the fan is to maintain air flow and compress it (or increase its enthalpy). Then, flow is really accelerate in nozzle creating thrust. Inside nozzle, pressure is converted in kinetic energy and this is not so far from what Yakup Seker call "Bernoulli's principle".

A bypass fan provides thrust in the same way a propeller provides thrust: by increasing the energy content of the gas mass passing through the disk.
The added energy is most effectively converted into thrust by allowing it to expand until internal pressure is equal to ambient pressure, so all added energy is converted into kinetic energy. This expansion takes place in the cowling behind the fan.
But the initial energy addition is a mixture of both increased pressure and increased velocity: the gas will require time to accelerate to the outlet velocity.

It doesn't bypass everything, just the combustion chamber.  Notably, the air still goes through a fan.
High-bypass turbofan engines make most of their thrust from the ducted fan.  Very much like a turboprop except the blades are smaller and enclosed by the cowling.
@Harper's answer on What is the difference between turbojet and turbofan engines? explains that nicely: a high-bypass turbofan extracts most of the exhaust energy from the jet part and uses it to spin the fan, instead of exhausting really high speed air from the jet part directly.
Low-bypass turbofans have a mix of thrust from fan + jet, while a pure turbojet has zero bypass, just compressor blades and no fan.


text:
What is this high wing, single engine aircraft?
I think it might be a Douglas aircraft.

Indeed a Douglas aircraft, namely the O-43, an improved version of the O-31 (longer wing and a new engine) which was Douglas's first straight-wing monoplane.
The O-43 was in turn developed into the O-46

THANK YOU SO MUCH!!!!


text:
Will N1 shaft turn at the same time as N2 shaft?
For Turbo Fan Engine CFM56-7, was wondering how come the Fan blades (N1 shaft) turns when I turn the N2 Shaft manually.
I thought N1 shaft is connected to the fan and booster rotor and LPT rotor and N2 shaft is connected to the HPC and HPT rotor and both are on individual spools.
So if the N2 shaft turns, by right anything on the N1 shaft will not turn right?

If wind blows from the rear the fan sometimes rotates backwards, even with the turbine idling. I've seen this at least once at the airport.

Both shafts are not connected directly. But there are still ways to transfer rotation from one to the other. The most obvious one would be the airflow generated by N2 turning the LPT. But also the bearings between both are not totally without friction and so will also transfer some rotation.

Yeah if he's turning the fan by hand it's going to be just bearing drag.

"bearings between both are not totally without friction", there is only one. On the other hand, N1 is also centered within frames by three bearings. So there is possibly more friction tending to maintain N1 stationary than friction tending to rotate it.

@mins I don't think counting bearings is a good way to estimate friction.

@Sanchises: Sure this is not accurate engineering, but when bearings of the same diameter, and all with balls, are not lubricated, I believe they won't be very different. In addition #1 which is on the fan shaft (rotating with N1) is a large one, likely the one with the most friction when not lubricated. So you're right, but let see if a mechanics can confirm or deny.

I still don't understand. If you turn the Fan, the LPT will rotate, If you turn the N2 via the handcranking pad, HPC and HPT will rotate. N1 and N2 shaft are both individual shaft controlling different things. If N1 turns, N2 will not move right?

On a CFM56, there is an intershaft bearing between the N1 and N2 shafts (#4 bearing at the aft end).  So for this engine, yes, some slight friction in the bearings can transfer torque between the shafts. This is also true for some cousins of the CFM56 like CF34-10 and F110.  However, for the majority of jet engine designs, bearings connect from the rotor to the stator, not rotor to rotor.  So for most engines, bearing friction cannot transfer torque between shafts.


text:
Is this a Janet Airlines 737 at Area 51?
I was looking at the satellite image of area 51 on google earth and i noticed an airplane that was taxiing alone on area 51 at 37°14′0″N 115°48′30″W or (R-4808N) could this be a Janet airlines Boeing 737 from Las Vegas that carries the government workers to and from the base??

I don't think the US military routinely declassifies information on the Stackexchange network so there's probably no definite answer.

@Sanchises, nothing can be declassified on SE, because there is no classified information in the first place.

Probably yes.
Janet Airlines operates the Boeing 737-600 (and some Beechcraft turboprops), which has a wingspan of $ 34.32 \, \mathrm{m} $ and a total length of $ 31.24 \, \mathrm{m} $. I measured the size of the aircraft using the Google Maps distance tool:

The dimensions of $ \sim 34 \, \mathrm{m} $ span and $ \sim 30 \, \mathrm{m} $ length match (within the accuracy of the Google Maps image) the dimensions of the 737-600. The white fuselage paint also matches the Janet airlines aircraft:

(image source: Wikimedia)
Most civilian aircraft are painted white of course, but military aircraft are typically not. The red stripe is not visible from above, so it is impossible to say for sure, but since I don't expect many other white 737-600s to fly to Area 51, I think it is a fair bet to say this is indeed a Janet airlines aircraft.


text:
Calculate g's per radian
I'm currently attempting to assign handling qualities to the A-4D, and I would like to know how to find the term:
$ n / \alpha = \overline{q} \times C_{L\alpha} / (W / S) $
where $C_{L\alpha}$ is the lift-curve slope. I think I could solve for the lift-curve slope by using the value $1/T_{\theta2}$ or $1/T_{P2}$, the phugoid frequency, somehow, but I cannot find that equation.
I'm not given a chart of the change in lift-curve slope per Mach number.

Who or what is A-4D?
Is this homework?

A-4D is the airplane assigned-- a military fighter pilot that could reach transonic speeds. It's a project I am doing for a class. I can find the lift-curve slope before before M=.6 using a certain equation I got from a NASA document, but the A-4D achieves up to M=.9, so the compressibility of the gas affects the lift-curve slope. A plot of lift-curve slope (lcs) for a plane shows that the lcs is constant until about M=.4, then you get an exponential growth as M approaches 1. I am either trying to find a plot of this for the A-4D or an equation for lcs that works until M=.9.

I would prefer the equation that I asked for above because that equation was developed from empirical relations, so it is usually close to the actual lcs(lift-curve slope), but if you have a graph of Mach number vs lcs, that would work better since those are the actual, tested values.

The solution that I needed is the following image:

It would be helpful for others to explain how your determined the equation

The equation posted was incorrect; it didn't work well for different values of w_sp. This here is the empirical data for just this one plane.


text:
If the RMI heading rose is stuck, would the needle still display correct bearing?
If the RMI (Radio Magnetic Indicator) heading rose gets stuck, would the RMI needle still display correct QDM (magnetic bearing to station)?

Define what you mean by “correct”?  How would you read the needle? Is the question “Does it display correctly” or “Can the correct information still be derived?”

@Jim: can the correct information about QDM be derived?

@SachinChaudhary Please always edit your question to include all information when asked for clarification. People shouldn't have to read through the comments to understand the question.


text:
Does TCAS II work and give RA with Mode C or Mode A transponders?
What's the minimum requirement for TCAS II RAs to be generated? Will we get RA if we have mode C transponder and the other aircraft also has mode C? Will mode A work as well?

TCAS II is based on the Mode S protocol.Aircraft with TCAS II on board are equipped with a Mode S transponder.
If the other aircraft is Mode A only (i.e. no altitude reporting) TCAS II will track the range and bearing of the traffic an will only provide Traffic Alerting (TA) for that traffic. Since the relative altitude of the traffic is not known, Resolution Advisories (RA) cannot be generated.
If the other aircraft is equipped with Mode A/C but not mode S, TCAS will track range bearing and altitude of the traffic and provide TA and Resolution Advisories (RA) for that traffic.
Reference material: FAA TCAS II v 7.1 introduction booklet


text:
Are the same units used for stations and waterlines?
I'm trying to decrypt a US aircraft manufacturer's plan. Could W.L. (waterline) and Sta. (station) references use different units?
For example, I have different distances from W.L. 0 to W.L. 200 and from fuselage Sta.3000 to Sta.3200. Are these references always in inches?

If I had to guess, I would say that imperial units aren't used, and what you are looking at is millimeters. If the fuselage started at Station 0 and ended at Station 3200 and was in inches, that would mean the fuselage was 266 feet long. An A380 is only 239' long.

Thanks for your response. It is a plane longer than the A380 indeed, never build , Boeing 2707-200. Found it was supposed to be 318' long. On the plan i'm working on , the nose starts at Sta.200 and fuselage ends at Sta.4016. It can't be millimeters.

Edit : 4016 - 200 = 3816 and that is 318' , so Stations are in inches for sure... But I don't understand that smaller W.L units.

What is the distance that you measure for the water line?

OK… I think I understand why.
That line noted W.L. is not the true WaterLine on the Plan, it’s used to mark the angle with another angled line noted « Ground line for minimum ventral clearance… » starting at the base of the main LG. Just for angle reference with the clearance line.
Should have noticed that , the same W.L line is legended as « W.L. (ref) » on another sheet .
So the true W.L. is lower, but not traced on the plan.
Thanks for your help anyway :) And sorry for the inconvenience.

Related http://aviation.stackexchange.com/questions/3863/what-is-the-coordinate-system-used-in-an-aircraft

Related: 2707-200 blueprint at Etsy.

Coordinates should always be in the same units. For a US manufacturer, that will be inches. The SI units are generally millimeters. This makes it much easier to locate coordinates, and for calculating things like volumes or distances.

Imperial units of millimetres?

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text:
Why does flight duration differ for the same flight?
I was checking the flight duration between two places over a 2-3 month period. The flight duration for the same flight is different for different months. For example, some days the flight takes 13 hrs 10 minutes and some other days it's 12 hrs over the same distance. How does this happen? Moreover, this data is available long before the departure of the flight; I am curious to know the reason. What are the factors that decide this?

It could just be seasonal route changes, is this a single flight, or a flight with connections?

Offhand the things that come to mind are seasonal wind changes, position of the jet stream, current weather (as opposed to seasonal), traffic and or oveflight permit changes requiring different routing, different equipment at times, and different projected loads (which will change time to climb. And there are others. JFK to Tel Aviv in a 747-200 back in the 1990s could be anywhere from 10.5 hours to 12 hours.

@RonBeyer This is a single flight.

@ymb, Related a bit, I had read the answer before posting this question.  I posted this to know whether only wind or any other additional factors are there. Thanks for your comment.

Related

could you make a specific example?

I'll expand on the other answers here.
Wind: The biggest factor in this is wind. Winds at common cruising altitude can sometimes reach well into the 100 Knot spectrum. Keep in mind that this can be in any direction. So lets say a long haul flight has a 100 Knot headwind half the year and a 100 Knot tail wind for the other half. That's a 200 Knot ground speed difference which can really make an impact on flight time.
ATC Holds Vary: ATC for various reasons may put a plane into a holding pattern on arrival. This may add to the time spent in the air for a given flight depending on the hold.
Landing Slots: There are 5 high density airports here in the US (and presumably others elsewhere) that require planed ahead landing slots. If the slot time changes but the departure time remains the same an airline may chose to slow the plane a bit (or speed it up a bit) to compensate.
Aircraft Loading: Aircraft efficiency (and subsequently speed) will vary a bit with the loading of the aircraft. Since not every flight on a given route is loaded equally there may be efficiency gained or lost as a result of loading.

Predeparture de-icing procedures.

Several possible reasons:

different equipment (not every aircraft flies at the same speed)
different routing
known seasonal changes in high altitude winds (which can prompt routing changes)
extra time built in in some periods for historically experienced frequent delays during those periods (e.g. in summer when a lot of inexperienced travelers with small children are expected, boarding and deplaning tends to take longer than in spring and autumn when there's more business travel).

I'm sure there are other reasons as well.

I was hoping for a specific example, but based on your statement that

some days the flight takes 13 hrs 10 minutes and some other days it's 12 hrs over the same distance

I suspect that you are determining the flight duration from the published schedules available to the public, that use local times for arrivals and departures, thus I would like to add a possible alternative to the ones proposed in the other answers:
Daylight Saving Time: different countries enter/leave (if they use it) DST in different dates. Example: the US and the UK change to DST 2 weeks apart, having a difference of only 4 hours between New York and London in that period, while normally they have 5.

and the downvote is because?

I guess because question quite clearly states that the duration is based on observation, not schedules... ?

@TomekCejner you could be observing the schedules. Don't assume everyone is a native speaker. If I "check" the flight duration of a flight over 2 moths, I do it online.

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text:
Do pilots lose their licenses following a gross misdemeanor conviction?
Can you have a conviction for a gross misdemeanor and still keep your private pilot's license?

Depends, is it a dwi or drug conviction?

Related

The most important thing to say here is that the only way to get an answer for a specific case is to consult an aviation attorney. Don't rely on any answers you get here!
Having said that, the general answer (that may not apply in every case) is that the FAA is primarily interested in alcohol and drug actions and convictions, including driving offenses and drug transportation. Pilots have to report those per 14 CFR 61.15, and again in any future application for a medical certificate:

Do I have to report anything other than alcohol and/or drug related
  convictions?
Yes, under 14 CFR Part 61, you must report alcohol and/or
  drug related administrative actions, whether a conviction took place
  or not. Arrests, administrative actions and convictions are also
  reportable under Part 67, the airman application for a medical
  certificate.

AOPA has a good explanation of the reporting requirements and their Pilot Protection Service can help with medical and legal issues. But it isn't a foregone conclusion that you lose your certificate, at least in 'simple' DWI cases:

A single driving while intoxicated (DWI) arrest, conviction and/or
  administrative action usually is not cause for denial provided there
  are no other instances or indications of substance dependence or
  abuse.

Leaving aside alcohol and drugs, if the misdemeanor had nothing to do with aviation then it's unlikely to come within the FAA's scope. There might still be some odd theoretical possibilities, like if the misdemeanor conviction attracts the TSA's attention and you're flagged as a security risk (see 14 CFR 61.18) but that's just playing with 'what if' scenarios. Again, you need to consult an aviation attorney for advice on specific cases.


text:
When are you allowed to use a call sign that is not the aircraft registration?
Some General Aviation pilots use their aircraft registration as a call sign, like C-ADYDJ for example. I've heard some use their aircraft type then some numbers like Cessna 45G. Then the typical airliners who use their company name then flight number, like ACA783.
When are you required to use your aircraft registration, and when are you allowed to replace it? If you are allowed to change it, can anyone use whatever call sign they want or is it limited to airlines only?

Are you asking about a specific country or set of regulations? For the US, this question and this one might cover what you need.

The “Cessna 45G” might be simply the abbreviated callsign—they are N2345G, but the controller might answer with just the last 3 symbols and from that point, the last three symbols is sufficient—and type added for the benefit of other pilots that may be looking for them, so they know the kind of plane to look for.

Whatever call sign you use must be registered. Making up a call sign is severely frowned upon. Here's an example of a pilot that was going for a "vanity plate" look in his call sign WITHOUT authorization.
https://aviation.stackexchange.com/questions/83872/what-are-the-repercussions-of-flying-an-aircraft-with-an-invalid-n-number-on-the/87102#87102

For the US, this is covered in AC120-26L, or in a more human-interpretable way from an NBAA article.

When are you required to use your aircraft registration

By default unless you have a callsign

Can anyone use whatever call sign they want or is it limited to airlines only?

What you use must be registered. For international flights if you fly frequently enough you can get a 3 letter ICAO designator (SWA, DAL, UAL, etc.)
There are national callsigns which are detailed in that letter, and local callsigns which may apply only to your tower, TRACON, or center depending on who you talk to and what their own rules for issuing a letter of agreement to use it are.


text:
Is it possible to train yourself to not be a victim of spatial disorientation?
Spatial Disorientation is a big danger to pilots. In fact, when learning how to fly in low visibility, a big part of the training is learning how to ignore your vestibular system and trust your instruments. But even with that training, it's entirely possible for a pilot in a stressful situation to forget that and try to fly by feel. This is the root cause behind the Kobe Bryant crash, but it can also affect seasoned pilots, such as the Air France 447 crash.
There are several languages, such as Tzeltal and Guugu Yimithirr, that don't have words for relative directions such as left or right. Instead, every direction is described in terms of the cardinal directions North, South, East, and West. Thus, for instance, instead of saying "the salt is to your left", they would say "the salt is to your South" (assuming that you happen to be facing West at the time). To speak such a language, you would need to constantly keep track of which way the cardinal directions are. Such constant practice at maintaining their orientation gives them a fantastic sense of direction, to the point that blindfolding them and spinning them around doesn't disorient them.
Would it be possible, as an adult, to train yourself to keep track of your own orientation like that while flying? How would you even go about trying?

to the point that blindfolding them and spinning them around doesn't disorient them Citation needed?

@Sanchises Unfortunately, all the actual studies are behind paywalls, but this study references another study "in which a Tenejapan was blindfolded, spun around 20 times in a darkened room and, still blindfolded and dizzy, was able to point in the direction of batz’il alan, or “true downhill” (approximately 15° west of north)."

Sorry, but I disbelieve the assertions in the 2nd paragraph, particularly the suggestion that by crippling one's language (no "left" or "right"... does that also mean no "port" nor "starboard" on ships???) you can instill an infallible INS into a person's head. Significant claims require significant proof, and this smells strongly of absolute nonsense to me. Down-voted.

Also, spatial reasoning is entirely different than spatial orientation (the opposite of spatial disorientation). The linked article mainly discusses the former; the anecdote about the dizzy subject pointing to North correctly is no basis for anything without significant corroboration.

I don't think the AF447 report even mentions spatial disorientation. That accident wasn't caused by that, i.e that the pilots would react on the urge of their kinesthetic sense over the instruments, but rather by loss of situational awareness, in this case meaning the pilots didn't understand what the instruments are actually indicating.

Ironically, a popular aviation YouTuber posted a video about this exact topic only hours before your question. The video shows the pilot undergoing Spatial Disorientation training in a specially designed simulator and includes links to the company where you can book such a training yourself.

@Jorg I also found this so strangely coincidental!

I’m voting to close this question because it's based on a number of false premises, and makes no attempt to back up some very questionable statements.

@JörgWMittag I promise that was a coincidence, I haven't seen that video, but I'll definitely check it out.

@GdD I didn't include references because I didn't feel that part would be important. The basic question (Can you train to avoid spatial disorientation) stands on its own, the discussion about people that can do it because they were basically trained from birth was just to illustrate the concept.

@HiddenWindshield Apologies for the reactions, downvotes and proposals to close your valid question, from always the same users. They can earn gold medals with this behaviour you see.

Voting to keep this question open due to it being studied and trained, re the actual DISO training device. And getting pretty disgusted with some members and moderators of this community.

The main problem that leads to spatial disorientation is sustained normal rate turns, and the direction of turn, or the direction at which you stop the turn, doesn't really come into it as far as that goes.
You roll into a turn, you sense the heading change in your inner ear, but over time the fluid in the horizontal cochlea catches up to the rotation and the turning sensation goes away.  You roll out of the turn, and now the fluid in the horizontal cochlea keeps going.  The resulting sensation of turning the opposite way, even though you're wings level, is quite intense, and what happens is, unless you catch yourself doing it, you will apply control input to roll back into the original turn (to get rid of the opposite turn sensation) without realizing it.
By the time you do catch yourself, and roll back to wings level, the wrong way sensation comes back and around you go again rolling back into the original turn, until you catch yourself again, and over and over, and you're getting a little bit dizzy, and then the final straw; you do something like look down and get the vertical cochlea fluid going, and yikes your head starts spinning every which way, and you're done.  That's the kind of situation Kennedy found himself in.
I'm not sure any kind of directional awareness other than observing the compass would help with this, because the entire exercise involves completely ignoring your directional sense.
The disorientation trainer that @Koyovis describes in his answer isn't widely used as far as I know, but it would be installed at every instrument flight school in the world if I was King of The Flying World, because the ability to keep up a sustained rotation, whether fast or slow, is not a feature of IFR and Transport category flight simulators and it really should be.

Yes indeed it is possible, and there are specific Disorientation trainers in use exactly for this purpose. The DISO above is one I have worked on, it is a simulator mounted on a 6-DoF motion platform, with a rotational system in between the cabin and the motion.
The subject would be flying, then would experience a spin, then would resume flying again while disoriented from the spin. Reason is that there have been accidents that occurred after a pilot recuperated successfully from a spin, but because of dizziness would then lose control a second time and not be able to recover.
The trainer has controls and instrumentation for flying fixed wing fast and slow aeroplanes, and helicopters. It has been in successful operation for over a decade.

As you may already know since you linked the wikipedia article about spatial disorientation, it's not really just about maintaining awareness about left/right, north/south etc. It is about one's orientation in 3d space, and in the specific case or being in an aircraft, which can be manuevered to create all kinds of false cues as to in which position one is, and what it the actual cause of accelerations felt, there is no way a human can maintain full spatial awareness without the aid of visual cues. There are good answers on that here, and research on the topic is clear:
https://aviation.stackexchange.com/a/84947/42636
https://aviation.stackexchange.com/a/84954/42636
https://www.aopa.org/training-and-safety/online-learning/safety-spotlights/spatial-disorientation
Humans can only learn to act properly to mitigate the effects of spatial disorientation, but full "immunity" is not possible to achieve.
As to the claim that language would affect the ability to maintain spatial orientation, there is no proof that I know of, and if there was, we surely would know about that. The study you provided a link to did mention a case in which a person was spun 20 times in a darkened room blindfolded, and was still able to maintain sense of orientation. This was not, however a "study", but a "report", and as such carries very little, if any, scientific value. We do not know how the experiment was carried cout, it may have had serious flaws in it. The footnote about this report states:

Levinson (2003) also reported formal studies showing that speakers of languages that use geocentric systems (Tseltal and Hai||om) were more accurate than speakers of languages that use egocentric systems (English and Dutch) at pointing to distant landmarks. However, the testing situations (type of environment, distance travelled, how participants arrived there, relative familiarity with surrounding, etc.) varied between the comparison groups (e.g., Dutch vs. Hai||om), making comparisons difficult

So, to say the least, no proof whatsoever that a language can provide protection against spatial disorientation within the scope of aviation.
Indigineous people, one's that are not as disconnected from nature as us city dwellers, can read their surrounding quite well to determinen geocentric directions even if no sunlight is providing shadows. Most trees have  more foliage on the southern side, erosion varies according to the amount of direct sunlight on rock formations (this varies greatly depending on type of rock), plants and animals prefer inclines of specific direction etc. People who rely on a geocentric system most likely have a constantly updating map in their minds about how objects are oriented. When they enter a building for example, the orientation of this building and its inner structure is locked into the map, and they can continue using the orientation of the geocentric system. If the building had no windows, and it was slowly rotating, the people inside would very quickly lose track of the geocentric coordinates, unless they had very acute magnetoperception, which humans do not have.

The last paragraph with the slowly rotating building exactly would screw up my spacial  orientation ability. however it would be reset the instant I saw a recognizable landmark. The other thing would be a maze where the walls move and change orientation. Disorientation could be increased by recognizable pasterns between wall panels changing.

There is training to be more resilient to the effects of disorientation, but that is not the same as being resistant to the actual disorientation. Basically the training will allow a pilot to condition to the sensations and practice correct planned responses so there is not a combination of disorientation with confusion or panic. Basically practiced reactions and habits for more reliable recovery. The disorientation still exists but it is shorter and has less negative impact.


text:
Do you need to have a raft if you're in a seaplane?
One of the basic rules of flying over water is that you need some kind of raft if you're out of power-off glide range from land. Does that also apply to seaplanes or amphibious planes?

Are you asking a pure regulation question, as in you are required to, or what is considered more general good sense?

@GdD This is a pure regulation question. Good sense would obviously say to take a raft, even if you're not required to.

Here is an answer I found after a few minutes of looking up regulations online.

Federal Aviation regulations require carriage of FAA approved floatation gear when operating under Part 91 for hire (FAR 91.205(b)(12)), but Part 91 flights not conducted for hire are not required by the FAA to carry floatation equipment.
It is worth noting that local authorities, including state, county and municipal authorities, may require that all vessels, including seaplanes, carry U.S. Coast Guard approved floatation gear on board.

Found on the https://www.seaplanepilotsassociation.org/resources/faq/operations/ website.

'floatation gear' in this case could just mean Personal Floatation Devices (i.e. life jackets). is there something else that specifies that it's a raft?

"Flotation gear" - you mean those gigantic pontoons bolted to the bottom of my plane? NOTE: according to Merriam-Webster, there's only one a in flotation, but floatation is a less common, but still correct spelling. Who knew? Why? Who cares?


text:
Why is the battery turned off for checking the voltage on the A320?
Preliminary cockpit preparation section requires BAT check for 25.5V with BAT off (The beginning step). Since BAT indicator always show respective voltage, why they must be switched off?

The voltage varies with what is connected to the bus.

Adding load will, for every electric source, reduce the voltage. And you wouldn't know how much is still OK without also knowing what is powered.
When the battery is charging (e.g. from ground power), you'll see the charging voltage even if the battery is empty.

With battery off you remove this variability, so they can give you exact number that signifies the battery is sufficiently charged.
(IIRC there are few things on the hot bus that are always connected, but their power consumption is known, so you check the battery under well defined conditions)

I'm not a pilot and don't know a thing about airplanes, but... in general you should always measure a battery with a load attached. Measuring without a load will give false readings.
Care to explain why this is different for airplanes?
(except for the charging on the ground part. That makes sense)

@Opifex I usually check batteries with and without load. Either reading won't give you the complete picture, both will. For example, in case of a (partial) short, the battery looks damaged under load while it's not the batteries fault.

@Opifex, measuring without load (well, with little load; even the voltmeter generates some load) gives you different readings than with load, but they are not false—you just have to be aware of the different voltage-charge curve, which is why it requires 25.5 V on what would be called a 24 V battery. On the other hand measuring with load risks measuring the ground power instead by mistake, which would be a problem.

@JanHudec I doubt that a user of a device (a pilot using an airplane in this case) would know the voltage-charge curve for the particular battery that happened to be installed in this plane at that particular moment. Especially because the curve would also be dependent on temperature and age of the cell. Measuring without load will give you a significantly higher reading, even if the battery is already broken. For example, a broken car battery can easily measure 12-13V, but once a load is applied it can dip to 6V.

@Opifex, the user does not need to know the voltage-charge curve, the manufacturer has to. And the manufacturer does, and provided an exact value to check for. Yes, a broken car battery can easily measure 12V unloaded, but it will still be lower than a good one. By 0.1. Well, the criterion is 0.1 here. 25.5V, good enough, 25.4V, must charge for 20 minutes, then check again, if not 25.5V, take out for maintenance. For a battery with 24V nominal voltage.

This check is done if the aircraft has been parked without ground power for more than 6 hours. The thing is that the LCD voltmeters for the batteries in the overhead panel is connected to the battery HOT BUS and they tend to draw power even when the aircraft is cold and dark (i.e not powered).
If the aircraft was parked like as mentioned, you get in the aircraft and check the battery voltmeters to see if the battery voltage is above 25.5 V. If they are below that, you need to get them charged before commencing the flight. To do so, you turn on the batteries (set them to AUTO) and then connect the aircraft to a Ground power unit (GPU). This will begin a charging cycle and it takes about 20 minutes to charge the batteries according to the Airbus FCOM. During the charging, if you look at the reading on the voltmeters you will simply see the voltage supplied by the GPU and not the batteries. When the batteries are charging, the BCL (Battery charging limiter) connects the two batteries to the DC BAT BUS. This bus is powered by the GPU when the aircraft is powered by it and when the batteries are charging.

When charging the two battery contactors are closed and the batteries are connected to the DC BAT BUS.
Once the 20 minutes is over, you turn off the batteries to make sure that the batteries are isolated from the DC BAT BUS. This will ensure that the reading on the battery voltmeters come from the Battery HOT BUS and gives you the actual voltage of the batteries and not the voltage from any other source. When the batteries are fully charged the BLCs will automatically isolate the batteries from the DC BAT BUS. In flight for instance, the voltage you see in the voltmeters is the actual volatage of the batteries because more often than not they are fully charged when in the air.

Thx dude.This is very practical precedure and exactly in SOP.


text:
How do you clean B737 Wheel Wells?
just wondering, is there any tools used to clean main/nose landing gear bay? I was thinking some machine with steam water or hot water high pressure and solvents.
wondering what is the best cleaning options for bays of B737 or A320 wheel wells.
or... perhaps brush and wiper? a little harder to remove CPCP

One option is to dry ice blast it.

best idea so far but any limitations regarding the pressure? AMM lets you use it? and what is the best quality machine for this

@SamerAlKasaji those links have some machines listed, you will need to check your aircrafts documentation or contact Boeing for proper procedures and limitations.


text:
What kind of assistance can another aircraft provide to an incapacitated pilot?
A recent incident unfolded as follows:

An aircraft overflew the planned destination and did not respond to radio calls on any frequency.
ATC decided the pilot might be incapacitated and asked another pilot whether he could get close to that aircraft to take a look.
The other pilot did that and observed no reaction to signals such as rocking the wings or extending the landing gear, however the incapacitated pilot was changing the course slightly to maintain separation.
Eventually the pilot resumed radio contact (speaking in a slurred voice) and upon insistence from ATC landed at the closest airport without further incident. All this time ATC was asking the other pilot whether they would still stay in the area, which they did until the landing.

There’s a VASAviation video with the entire radio conversation.
How can the other aircraft help beyond what they already did? Why did ATC want them around after getting in touch with the incapacitated pilot? Despite the aircraft belonging to the Royal Flying Doctor Service of Australia, it’s not like they could provide medical help. What else could have happened after radio contact was restored that would have necessitated some kind of action from the other pilot?

See https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_crash for a similar incident - the reports from the aircraft sent to intercept give an idea of the kind of things ATC were looking for.

Most obviously, what makes you sure the stricken pilot won't suffer a relapse?
At ground level, if you were the original Good Samaritan, would you really ask "Are you OK, Buddy?" and if the victim said "Yes. Thanks, and I'll be fine" just walk away?
Would you not more likely make sure Mr Vic got to help, whether that was merely the Samaritan's inn or for instance a hospital or police station?
Should a pilot do less? Come to that, don't pilots have a legal duty to do that much?

This is speculative and I haven't looked at the links you gave, but I can think of a few things:

Having another aircraft there gives ATC a way to gather information that they otherwise couldn't. For example, if the second pilot had observed that the 'incapacitated' pilot was actually awake and alert and there was a second person in the cockpit brandishing a gun, I think it's safe to assume that the response from ATC, law enforcement and the military would have been different.
The worst case is that the incapacitated pilot never recovered and simply crashed. In that case the second pilot could give ATC a precise location for rescuers, which could be important in a more remote area. Especially if ATC had no radar coverage.
The incapacitated pilot could have recovered but still been disorientated and unable to communicate properly. It's possible that the second pilot could have led them to a nearby airfield. That would still require some understanding and communication between them, and the second pilot might not have been comfortable with doing it, but it's an option.
It's possible that the incapacitated pilot recovered but couldn't talk directly with ATC. That could be because they drifted down to an altitude below ATC's radio coverage, or couldn't change frequencies, or whatever. The second pilot could relay calls from ATC in that case, assuming that they could work out which frequency the incapacitated pilot was on. Relaying calls from ATC to another aircraft is fairly common.

I'm sure we could all come up with other ideas, but I think the first point is the most important: when something strange is happening then it's best to gather as much information as possible.

All good points, especially last one. I've been the 2nd plane pilot myself once. Other plane was flying low in river valley between mountain ranges, which got it out of radio and radar contact with ATC. I relayed for ATC. Was a training flight. Instructor had stroke, student (2nd time behind controls) was flying. He didn't know how to navigate back to take-off airfield, but he recognized the river and knew downstream was another air-field (I was going there too). ATC asked me also to keep a visual on his plane-handling and check if he followed instructions, while they guided him in.

Continued... He did a very good job of his first solo landing :-) Ambulance was waiting next to the field. The instructor was rushed to hospital and eventually made full recovery.

Having been pilot in an otherwise empty aircraft and having a very big (but drawn out) emergency, I can tell you that knowing that others are routing for you gives you quite a boost.  Seeing another plane out there and knowing he or she is there to help, even if there's not much they can do, really helps psychologically.

@Tonny Oh man, well done on the part of the student.

@Tonny Well done all around.

In the particular incident you are referencing, the incapacitated pilot was delirious with hypoxia. After the spotter confirmed that the pilot was conscious and non-evasive, ATC asked the spotter to remain nearby and try to get the pilot's attention visually while chanting "oxygen oxygen oxygen" over the radio. They understood that in his compromised state, he was more likely to get the message if he could see AND hear something to snap him out of his stupor.
Beyond certain specific actions, (like in this case) there is not much that another aircraft can do to help with medical issues, beyond providing moral support. Sometimes, though, that may be just enough.

Speaking of oxygen oxygen oxygen, couldn’t ATC transmit such a message themselves?

@RomanOdaisky: Of course, and I think they did a few times. They just thought it might sink in more with another pilot pointing to his face while trying to get the message across.

@RomanOdaisky: SmarterEveryDay did an episode on hypoxia: https://youtu.be/kUfF2MTnqAw?t=380 You can clearly see that the instructor tells Destin "If you don't get back on oxygen now, you will die!", and gives him instructions what to do (put on the mask, flip the switch). Destin responds laughing "I don't wanna die", but clearly does not understand what is going on, despite the instructor telling him exactly what to do. As Aaron said, maybe ATC was hoping that with verbal instructions and visual cues, the pilot might understand better.

@JörgWMittag This assumes the 2 planes can get close enough that the pilots can see eachother directly - a somewhat risky maneuver, especially if one of them is incapacitated.  I guess we're talking about small planes here, but this would likely not be an option for larger ones.

ATC may have wanted the other plane to keep an eye on them in case they crashed, which could save hours or days of someone else trying to find it again. Such a delay could make a life-or-death difference to someone who survived the initial crash but with serious injuries.

There was an interesting example of this in the UK perhaps ten years ago. The solo pilot of a small plane lost his sight while in the air, an RAF instructor went up in a Tucano from Linton-on-Ouse and (eventually) guided him to a safe landing. I'm afraid I have no information on whether the pilot flew again.
This is obviously very similar to the example recounted by @Tonny, which suggests that it might be a comparatively common scenario; and they're clear examples of a pilot on the scene being able to assist rather than just report.
Later: found this from November 2008 http://news.bbc.co.uk/1/hi/england/north_yorkshire/7715345.stm Reports elsewhere suggest that the pilot regained at least part of his eyesight.
Also https://forums.flyer.co.uk/viewtopic.php?p=737791 although I can't get the link to the talkdown recording to work.


text:
When can airliners fly from Israel over Tunisia's and Algeria's airspace?

Per flightradar24, on August 25th 2019, an Air Europa Boeing 787 flying from Tel Aviv to Madrid flew over Tunisia's and Algeria's airspace.
I thought flights departing from Israel or flying to it are banned from the airspace of Arab countries that don't have diplomatic relations with Israel.
For example, flights between Israel and India fly around the south of the Arabic peninsula. Flights between Israel and South America fly north of the Gibraltar straights.
Does someone know how did this happen, if it is a one off or a change, who authorizes this. Maybe this can happen in case of bad weather or an unplanned contingency.
While I did not find an official source stating that such flights are forbidden from those two countries airspace, see here for an informal one: https://ops.group/blog/countries-with-bans-on-flights-to-israel/
Thanks

Could you add a source for the claim that flights from Israel are supposedly banned from Tunisia?

Did not find an offfical source. Unofficial one: https://ops.group/blog/countries-with-bans-on-flights-to-israel/

While Israel may be restricted from Middle Eastern Arab countries, North Africa is a bit different. The EASA has a list of countries they have a working agreement with, which includes both Israel and Tunisia

As part of the process of creating a wider Common Aviation Area with its eastern and southern neighbours, the EU negotiated a comprehensive Euro-Mediterranean agreement with Tunisia which has been initialled on 11 December 2017.  This comprehensive agreement will result in an increase in the number of direct flights and boost trade and tourist flows between the EU and Tunisia.  Beyond market opening, the agreement also provides a modern framework and high standards for a wide range of aviation issues, such as safety, security, passenger rights, air traffic management, economic regulation, competition issues or social aspects.

As to Algeria (not in the EASA), the answer is probably more mundane: airspace fees

Many countries use airspace fees as a form of revenue and, sometimes, as a form of leverage during political negotiations. This causes prices and routes to fluctuate, with airlines subject to different policies. Costs are, of course, transferred to travellers, while airspace restrictions can significantly limit the options available to certain destinations.

Algeria uses France's ENNA to collect their fees

Overflying navigation fees are generally imposed by the country’s civil aviation authority (CAA) although some countries have other entities responsible for their issuance, such as the airport authority, or specialist local government bureaux. In Algeria for example, responsibility lies with ENNA, the National Enterprise for Air Navigation.

As such, Algeria doesn't want in Israelis in their country, but probably doesn't mind their money to fly over nearly as much.

and as the airline in question is Spanish rather than Israeli, they'll have even less objections to them being there.

Money, dear boy.


text:
Is it likely that an aircraft could have been near 10° 08' north at local midnight August 26/27, 2003?
Edit: The astronomical data turned out to be different. I'm keeping the constraints below as they where, but those are not relevant to finding the closest person to Mars.
This is part of an effort to determine which human has been closest to Mars. As Apollo astronauts and ISS space station crew are ruled out, this someone must have been on Earth
That's why I'm turning to you. Planes are frequently flying 10km or higher, much higher than any mountain on Earth, and passengers and pilots are therefore higher up than any people on the ground.
There are some rather delicate restrictions:

The aircraft must have been very close to 10° 08' north. There's a quickly growing altitude penalty for being far from this..

The aircraft must have been at this latitude at local solar midnight

The longitude is not overly important. For the western hemisphere, the date is August 26/27, for the Eastern hemisphere, it's August 27/28. Africa can be either, but has a 700m altitude penalty be default.

Is night-time air traffic dense enough for this place to exist?
From initial research, busy airports such as Singapore and Kuala Lumpur are south of this line

what kind of data/proof would you require to accept a yes or a no?

@Federico Some estimate of how many planes are actually flying in relevant routes would be enough. I have little hope for identifying a specific flight.

The southern tip of India and island of Sri Lanka virtually touch the line; as nearly as I can tell, the island of Formosa (Taiwan) is hidden under it, as is Hong Kong.

Over 1 hour, it increased by 31 km.  From the other question. So for extra flight altitude to me meaningful, you need to look only 20 minutes around closest earth-mars approach. At what exact time was that? This will rule out 95% of place on earth

@Jeffrey The astronomical side of things have been updated beyond recovery for this question. I can't delete it as it already has an answer, but this question will not settle the original problem that motivated the post.

@ZeissIkon Taiwan and Hong Kong are around 22-25N nowhere near the line

Yes, it is very likely that an aircraft would be near that position/time/date as there are many aircraft that fly overnight flights from North American airports to and from South American airports, between Europe and Africa, and also between Asia and Australia.
For example, Air Canada has daily night fights from a Toronto, Canada to Santiago, Chile and both the outbound flight, and return flight, would often pass each other in that very same area and time. I would often operate those flights and we would chat with the crew of the opposite flight to exchange reports on flight conditions.
There are MANY other airlines with similar north-south routes operating overnight flights all over the world.

There are overnight flights between Europe and South Africa as well.

I'm accepting this answer as it illustrates the original problem of finding night time traffic over a latitude, which is likely somewhat reusable for other similar astronomical problems.


text:
How is the Flight Plan Data transferred into an aircraft/plane?
I know that pilots have to fill the ICAO standard flight plan and send it to the relevant CAA to be checked, updated if needed and finally approved before the flight takes off. what I am looking for is to understand how does the  aircraft receives that acknowledged flight plan data. I know that some airlines receive the acknowledged flight plan from CAA's and then send it to the aircraft via ACARS so the aircraft, is this the most common option or there are other option for the aircraft to receive the acknowledged Flight Plan? Please let me know.

First, as other answers have stated, you're not actually required to file a flight plan unless you're flying IFR. That having been said, if you do file a flight plan, there are several ways you can get it programmed into the airplane:
You don't
The flight plan is never loaded into the navigation system at all. It's either on paper or loaded into a tablet, and that's it. This is pretty common amongst small-aircraft private pilots.
Manually
The flight plan is printed or loaded into a tablet to get it out to the airplane, where it's then manually keyed in to the on-board navigation system. This was at one time the only way of loading a flight plan, and is still pretty common across all types of aviation.
Bluetooth
This is a pretty new option for the higher-end GA aircraft and charter aircraft. The flight plan is transferred from a tablet, laptop, or smartphone to the onboard navigation system via a Bluetooth connection.
ACARS or other data link
Yes, ACARS is used by the big airlines to transfer flight plans to aircraft. Note, however, that some commercial aircraft don't have the capability to automatically transfer the flight plan to the navigation system(s), it's printed out by the in-cockpit printer and keyed in to the navigation system as described above.

Thank you so much for your answer, I really appreciate the help.


text:
What is the estimate for total number of flight hours in the world?
Working on a type of estimate model for aviation and was wondering if there was an approximate total number of flight hours in a year across the industry as a whole?
Edit: Counting only Commercial Flights

AOPA says "The latest data shows general aviation flies more than 20 million hours each year". I think may just be in the US.  That includes me and my 50 hours.  They have a nice 2 page brochure on What is General Aviation?
https://www.aopa.org/-/media/files/aopa/home/advocacy/what_ga.pdf  Then you have all the commercial passenger flights, adding millions more ...

Are you including GA and military?

@ManuH just commercial Aviation, apologies for the lack of specification.

@PatrickMcClean no worry, that's also why comment are for (giving help to precise the question)

In 2018 there were about 37.8 million commercial flights. If we multiply this number with the overall average flight duration, we get the answer. Unfortunately I could not find a result for this directly.
We can however calculate it from the data provided by the MIT Airline Data Project. The data says there were 3,954 aircraft available on average in 2018 that accumulated a combined 13,398,545 flight hours with 3.82 departures per aircraft per day on average. This means the average flight duration was
$$ d = \frac{13\,398\,545 \, \mathrm{h}}{3954 \times 365 \times 3.82} \approx 2.43 \, \mathrm{h} $$
This is just based on various US carriers, so the world average might be somewhat different, but since US carriers fly a wide variety of flights from short domestic routes to ultra-long haul international routes, I assume this number to be close to the true answer.
The resulting total number of flight hours is then
$$ 37.8 \cdot 10^{6} \times d \approx \mathbf{91.8 \cdot 10^6 \, h} $$
This does not yet include GA traffic or military flights.

Great answer to a tough question, giving estimates (supported by sources) and resulting in a useful approximation (i.e. 91.8 x 10^6 h; or in words: a tad shy of 100 million hours per year)


text:
Why increase or decrease rudder when using elevator in turns?
In normal 30 degree bank level turns, instructors teach students that if you are to correct your altitude you also need to change your rudder input.
Why is that?
For example if you are descending in your turn you are to pull the elevator and also lessen your rudder input. And if you are climbing in your turn you are to push the elevator and push more rudder.
Is this because of you are tightening your turn when pulling elevator and therefore you are starting to skid and therefore you need to lessen your rudder to compensate. And if you are pushing the elevator you are doint the opposite starting to slip and therefore you need more rudder.
Or is there some other explaination to why you need to do this?
EDIT:
Hi,
no I think you have misunderstood the question.
They do not teach to use the rudder to compensate for pitch/altitude.
They teach properly to use the elevator. But they say that when you make a change with elevator to a higher nose you don't need that much of rudder than before. And when you use the elevator to push nose down there is more need of rudder.
The rudder change is just to compensate the need due to change in configuration. Not to use it to change the altitude.

Can you give more detail on where you heard this?  From several different instructors?  In what aircraft?  In what country?  I don't think I've ever had an instructor tell me this.  Langewiesche says something kind of the reverse of this in "Stick in Rudder"-- he says sometimes you want to use the elevator not the rudder to center the ball, especially in a slip (ball to low side of turn), but I've not found that to be accurate either.  We find the same statement in some of the earlier editions of "Modern Airmanship", but it was deleted from later ones.

Are you sure they weren't suggesting to roll out a little bit (decrease the bank angle) to help stop a descent?  This input would involve coordinated use of ailerons and rudder.  If you were basically carrying a significant into-the-turn rudder input throughout the circle, I can see where rolling out might use a touch of rolling-out aileron and a little relaxing of the into-the-turn rudder but still holding some into-the-turn rudder.  And sort of the opposite to help stop a climb.  Sorry, that might be a bit hard to follow.

Still, for turns that are only banked 30 degrees, I would think most instructors would not teach to use changes in bank angle to help stop a climb or descent.  That is more appropriate for much steeper turns, in my opinion.  Anyway, please try to tell us a little more if you can.

Just read your edits to question.  So your instructors are apparently telling you that as you raise the nose and slow down to arrest a descent, you'll find you need less inside rudder to keep the ball centered?   Again see previous requests for info as to what aircraft, what nation, etc.

Instructors that teach that to students are fools.  You should be using rudder only as required to keep the ball centered - period.  If you are applying rudder to influence the pitch attitude, to "help hold the nose up", this is very very bad, and leads to stall/spin accidents.
Rudder is mostly being used to counteract adverse yaw from the aileron inputs, and to some degree to correct for yawing motions caused by power changes.  But in any case it is strictly used to keep the tail lined up behind the nose in the airstream.  Anything else and you are skidding or slipping in the turn.
If you are in a 30 deg banked turn, and are descending, the total lift from the wings is insufficient; you need more elevator input, NOT top rudder, which creates a slipping turn, which will make the airplane flick over the top into a spin if you stall while doing it.
Don't overthink it. Ailerons to keep the bank angle, elevator/power to control the pitch and altitude/speed, rudder to center the ball; just do whatever it takes.

John, also, add power in a turn to stop descending to avoid excessive AOA with elevator.

Of course.  It's pitch/power together for speed/altitude control.

excuse the neophyte question, what does "keep the ball centered" mean?

@FlorianCastellane see https://en.wikipedia.org/wiki/Turn_and_slip_indicator#Inclinometer

If you've been flying long enough you don't even need a slip/skid ball and can just go by where the "apparent gravity" that your torso senses is. Slouching to the left, left rudder, and vice versa.  Plus if you don't have an engine/prop in front you can dispense with the inclinometer and just tape a piece of yarn to the windshield.  Gliders use yaw strings universally, and sometimes you see them on military jets.  More precise than a skid ball and you don't have to look down.

@Michael Hall. Elevator use changes the aircraft pitch angle to the relative air flow, and hence the amount of P-factor experienced by the aircraft will change. Since this is manifest as a yaw, an appropriate rudder change is necessary. John K. is correct—-this is not the way to teach turns.

Good point.  However, the original question did not specify that the effect operated in the reverse direction when turning right versus left, as would be the case with p-factor.  It would be good if the original question were clarified to address this.  Also I'm not sure how noticeable the change in p-factor would be during a typical correction of an unwanted climb or dive in a light plane.  Still, good point.

@ABC (original asker) please note comment above--

Yes, I understand that, I have just never noticed a perceptible need to use any rudder to compensate for minor adjustments in pitch.

With 30 degree bank from the ailerons, your wings create a centripetal force to make a turn. Now pitch and power are increased because the vertical component of lift is reduced, and the rudder makes the turn coordinated.
Adding elevator will not only lift the nose, but also add yaw - the same sine & cosine are at work. You reduce rudder to keep the yawing force constant. Yes, that is the whole explanation.
Just imagine a turn with 60 degree bank, or even knife-edge flight. Or look how a V-tail works on the early Beech Bonanza. It is all about splitting and combining force vectors.

How does the elevator induce yaw?

@MichaelHall, that depends on your reference frame.  In the reference frame of the airplane, no, the elevator won't induce yaw.  But in a gravity-aligned reference frame, the elevator will produce a turning force if the airplane is banked.  Extreme example: roll the airplane 90 degrees, then apply up elevator.  In the reference frame of the airplane, you'd call the resulting maneuver a "loop", but in a ground reference frame, you'd call it a "turn".

I understand, but that isn't my question.
The frame of reference for yaw is always the aircraft.  Bobby J said that adding elevator would add yaw.  I would like him to explain that.

@BobbyJ -- Sustained knife-edge flight is "uncoordinated".  The ball is way off-center.  Are you saying the same should be true at 60, or 30, degrees bank?  Yes a pitching maneuver can change the bank angle (think wingover or chandelle) but correcting for that should involve ailerons as much as rudder.


text:
What factors should be considered to select jet-pipe or flapper-nozzle technology for a primary control surface?
How is the servovalve mechanism chosen between these two mechanisms? what are their advantages and drawbacks?

"Which is better" questions are opinion based and will be closed. The "What factors" is the part that saves this one. You'd be well served to rewrite the whole question from that perspective.

I edited the question

It may be tough to find someone with enough experience in servo-valves to answer this, but I can add some (old) insight. The buyer of the valves typically won't be too concerned about the design. They want performance (size, weight, power, freq response, reliability, cost). I was involved in a study of these about 35 years ago. The end result was there was little difference in performance between them. The biggest difference we found was the jet pipe's failure modes to contamination were more benign but it wasn't enough to justify switching from the flapper style we had.


text:
Choosing $\phi/\beta$ in Lateral-directional control design
In designing the Lateral-directional controller for aircraft, there is a parameter called $\phi/\beta$ that is defined as the ratio of the magnitude of the bank angle to the sideslip envelopes in the dutch-roll mode. For example in MIL-STD-1797, a lot of requirements are based on this parameter. However, there is no clue how this parameter is chosen itself in the design process. How can one choose this parameter in the design process?


text:
Why is the fuel pump in the startup procedure for a Cessna 172?
I thought fuel pumps were reserved for fuel injected planes in startups and during critical flight phases for all planes?
However. There are some X-Plane flight tutorials that tells us to use fuel pump in startup of C172 aircraft as if we are flying a fuel injected plane. I don't think its necessary for an gravity fed engine but why would someone use fuel pump in a high wing carburetor plane start up? Isn't it a waste of battery?

I am in a hurry so I can't check which video was that tutorial sadly.

When you are playing a computer game, follow the game tutorials.  If you are flying a real aircraft, follow the POH.

Many 172s are fuel injected.
I've flown both carbureted and injected 172s.
On a carbureted model, you prime by pumping the primer between 2 and 5 times.
On a fuel injected model, you prime by running the fuel pump for about 3 to 5 seconds with the mixture open.
As for why you do that, the short answer is because the POH says so.
The more precise answer is that gravity feed alone is not enough to push fuel through the fuel injectors (which are very tiny little holes in the cylinders)

Correct, and the stock C172 in X-Plane is an SP so definitely a fuel injected version.

Typically, fuel pump is turned on to make sure it works, and then off. Fuel pump is only used in flight if gravity-fed fuel pressure from the wing tanks drops due to flying at extreme angles of attack.
Not a waste of battery, as you would be using electricity from the engine driver alternator.

Huh. Weird to see its not a part of the checklist.

It's on the checklist for my C177B, which uses the same arrangement.  See Page 4-12 of the C172SP POH  http://aeroatlanta.com/docs/aero-atlanta-c172sp-poh.pdf  6. Auxiliary Fuel Pump Switch -- ON.
7. Mixture -- SET to FULL RICH (full forward) until stable fuel
flow is indicated (usually 3 to 5 seconds), then set to IDLE
CUTOFF (full aft) position.
8. Auxiliary Fuel Pump Switch -- OFF.


text:
Can a Skylane fly without electricity?
Some Hobbs Meters uses master electricity switch to keep the track of time.
So what If an cheapskate Skylane pilot wants to fly without electricity to lessen rent?

Which main six instruments would keep working?
Would the engine fail? (There are both carburated engines
and fuel injected engines which complicates things a little bit)

I was once accused of this by a rental outfit. Turns out their Hobbs had broken.

Most Hobbes meters are activated by oil pressure and powered off the battery bus so you can't bypass it.

Captain Cheapskate aside, it is still legal to fly planes that have no electric system at all, such as the Piper Cub.

@SkipMiller flying without transponder in Class B and Class C is illegal as I remember.

@jonathanIrons, that is very true.  But there is far more airspace below Class A space that an airplane without any electric systems at all where flying a Piper Cub  or other non-electric equipped airplane is perfectly legal.  And the Piper Cub and other similar planes cannot climb up to Class A space anyway...

The engine wouldn't fail. Avgas powered engines use 2 magneto systems which are independent of the battery and alternator, so if your alternator dies or you lose the electrical system it will run as if nothing happened. Starting it does require the battery and electrical system though to run the starter motor. Aviation engines with computerized ignition systems have backup batteries so they will also not fail due to an electrical system malfunction.
As for the "6 pack" cluster of instruments 3 are not powered at all: Airspeed Indicator, Vertical Speed Indicator, and Altimeter. 3 are powered, although there is no hard and fast rule the Attitude Indicator (AI) and the Heading Indicator (HI) are usually vacuum powered from the engine and the Turn Coordinator is usually electrically powered. There are many exceptions to this.
So keeping the electrical system off doesn't affect the primary instruments much, provided the airplane stays in VFR. What captain cheapskate won't have for sure is any radios, transponder, GPS, ADF, VOR, or any other communication or navigation aids.
All these things you could probably do without on a completely VFR flight, provided you don't need communications. However, the engine temperature and oil pressure gauges, EGT gauge, and fuel gauges all work using electricity as well, and I'd really hate to lose those. A typical steam gauge Cessna isn't going to have an electrical fuel pump, but many piston singles do. Running without the electrical system means you'd lose that to, and that's considered an important safety system to back up the mechanical one in case of failure.

Like this video proves:
https://www.youtube.com/watch?v=fZtpLFICLec

Captain Cheapskate could use a separate radio, though. It wouldn't depend on the aircraft's electrical systems.

Need electricity for a Beacon Light.  Big discussion having it on all the time here
When to use beacon, anti-collision, strobe, logo, and navigation lights?


text:
Why were 'business jet' airliner designs so popular in the past?
Let's look at the MD-83 (was Microsoft too poor or they lazily didn't want to waste time to make it flyable in FS2004/FSX?) and the Learjet 35 (yes I used FS95/FS98 in the past).
Now, there are some "samish" things:

Engines on the back of the fuselage
Vertical stabilizers on the top of the rudder (maybe because engines take space in the back of the airliner?)
Wings on the back of the plane (let's be honest, the first time I saw that I felt like "How did this fly?" only to realize it was made in order to put CoMass near to the CoLift
Front of the plane is extremely long compared to the back of it (by back I mean the place that the wings and engine are on)
Engines are SLIGHTLY tilted to the ground

Why was this 'business jet' design so popular in the past for airliners?

Possible dupe of this question as well as this one and more info in this one

Now we have 4 interconnected questions on the whole exchange
Lets forget it ok ?


text:
What is the maximum allowed difference between two altimeters for flying in RVSM airspace?
What is the allowable altitude difference reading between two altimeters while flying inside RVSM airspace?

I added the FAA regulations tag because I noticed in a comment that you're looking for a FAR. If I misunderstood, you can just edit again to clarify.

Should not be double the allowed measurement error of the single device?

On the ground during the preflight check, the altimeters must be within 75 feet of each other.
In-flight the altimeters must be within 200 feet of each other.
I have been flying the B777 for about 8 years and I have never seen the altimeters disagree by more than about 10 feet, either on the ground or in flight.

Appreciate your response, that’s what I though initially I flew for a company that only allowed 50ft difference between altimeters in RVSM wondering if their is a FAR to back this up.

I couldn't find an FAA regulation, but AC 91-85B Authorization of Aircraft and Operators for Flight in Reduced Vertical Separation Minimum (RVSM) Airspace
Document Information page B-4 says 200ft:

At cruise FL, the two primary altimeters should agree within 200 ft
  (60 m) or a lesser value if specified in the aircraft operating
  manual. (Failure to meet this condition will require that the
  altimetry system be reported as defective and notified to ATC.) Note
  the difference between the primary and standby altimeters for use in
  contingency situations.

It also says on page B-3 that before takeoff both altimeters must be within 75ft of field elevation:

The aircraft altimeters should be set to the barometric pressure for
  local altimeter setting (QNH) and should display a known elevation
  (e.g., field elevation) within the limits specified in aircraft
  operating manuals. The difference between the known elevation and the
  elevation displayed on the altimeters should not exceed 75 ft

Piling on to an earlier answer, but with some more tangible references.  Noting that your post doesn't specify which country you're flying in, there does seem to be an international standard (defined by ICAO).  I highly recommend using this resource to help understand several relevant regulations.
Starting with the FAA...
The FAA regulation is found in Part 91, Appendix G.  The advisory circular referenced above is the most accessible way to process RVSM Requirements and is updated to the newest RVSM law (from Jan '19).
From the advisory circular:

A.5 Altimetry System Performance.
A.5.1 General. The statistical
  performance statements of International Civil Aviation Organization
  (ICAO) Doc 9574, Manual on a 300 m (1,000 ft) Vertical Separation
  Minimum Between FL 290 and FL 410 Inclusive, for a population of
  aircraft are translated into airworthiness standards by assessment of
  the characteristics of ASE and A-9 1/29/19 AC 91-85B Appendix A
  altitude control. The following standards differ in some respects from
  that document, but they are consistent with the requirements of RVSM
  and in accordance with 14 CFR part 91 appendix G, section 2.

Here, you see FAA concordance in spirit and substance with ICAO.  If you're interested in the nuanced details which defines a valid altimetry system for certification, you should read this entire section.  In short, it defines a max standard deviation of Mean Altimetry Symmetry Error (how much the altimeters differ) at 80ft, and 3 standard deviations at 200 ft.  This is then used to derive the inflight guidance found in Appendix B:

At cruise FL, the two primary altimeters should agree within 200 ft (60 m) or a lesser value if specified in the aircraft operating
  manual. (Failure to meet this condition will require that the
  altimetry system be reported as defective and notified to ATC.) Note
  the difference between the primary and standby altimeters for use in
  contingency situations.

Moving to ICAO, you can see ICAO Verbiage here:

In respect of aeroplanes for which the characteristics of the airframe and altimetry system fit are unique and so
  cannot be classified as belonging to a group of aeroplanes encompassed by paragraph 1, the height-keeping performance
  capability shall be such that the components of the TVE of the aeroplane have the following characteristics:
a) the ASE [Altimetry Symmetry Error] of the aeroplane shall not exceed 60 m (200 ft) in magnitude under all flight conditions; and
b) the differences between the cleared flight level and the indicated pressure altitude actually flown shall be symmetric
  about a mean of 0 m, with a standard deviation no greater than 13.3 m (43.7 ft), and in addition, the decrease in the
  frequency of differences with increasing difference magnitude shall be at least exponential.

Finally, it's interesting looking at the European Aviation Safety Agency (EASA) SPA Verbiage:

two primary altitude measurement systems. A cross-check between the primary
  altimeters should be made. A minimum of two will need to agree within ±60 m
  (±200 ft). Failure to meet this condition will require that the altimetry system be
  reported as defective and air traffic control (ATC) notified;

I appreciate your answer this is perfect I fly mostly domestic (US) but sometimes international this is great information. Thank you!

50 ft to know ground in canada.  check out this sad story where two pilots choose the wrong answer and paid the ultimate price.  they choose to set PM altimeter to match PF - bad news was the PF altimeter was the one that was reading 130 ft too high.
https://www.tsb-bst.gc.ca/eng/rapports-reports/aviation/2008/a08w0244/a08w0244.html?wbdisable=true

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text:
Why do some multi-engine aircraft have accelerate-go distance in their performance charts and some don’t?
I'm curious about why some airplanes have accelerate-stop distance (ASD) and accelerate-go distance (AGD) in their performance charts and some don’t include that. Does anyone know why?

Just to confirm, you're saying whereas the ASD is 'always' given, AGD is not?

So, if we use the Diamond DA62, the POH manual says...
The certification basis is JAR-23, published on 11-Mar-1994, including Amdt. 1 with some paragraphs elected to comply from CS-23 and additional requirements as laid down in CRI A-01 and published in the Type Certificate Data Sheet.
The certification basis for US registered aircraft is 14 CFR Part 23 effective February 1, 1965, including Amendment 23-1 through Amendment 23-55.
I don't have any JAR knowledge but I can comment on FAR's.
FAR 23.1585 f(2) and FAR 23.1587 d(5) says the pilot manual must include...

(2) Procedures and speeds for carrying out an accelerate-stop in
accordance with § 23.55.
(5) The effect on accelerate-stop distance, takeoff distance, and if
determined, takeoff run, of runway slope and 50 percent of the
headwind component and 150 percent of the tailwind component;

This specific Diamond aircraft was approved on February 1, 1965 and would have been required to meet FAR 23 but may have been granted some waivers based on JAR-23 approval. I don't know the requirements in 1965 but similar aircraft like Cessna and Piper Manuals had inaccurate information in the same time period.
In about 1985 the FAA wanted manufactures to update deficiencies in their manuals but the mfg resisted because the laws said a change would re-instate liability. Eventually congress passed a bill in 1994 that released them from liability after 18yr from mfg date and allowed changes to manuals.
I am most familiar with how this affected Cessna. Cessna manuals had deficiencies in "un-usable fuel", "emergency procedures", and "equipment operations". Cessna had addressed some issues such has equipment operations with separate "supplements". The FAA wanted all the information available to the pilot in a single manual.
Take for example the C-172. The un-usable fuel in the POH went through several changes i.e. from 1gal in 1967 to eventually 3gal in 2007 - in certain instances, even higher. The parts for the C-172 fuel system have never changed but the FAA got stricter (FAR 23.959) about calculating it.
One of the changes the FAA forced Cessna to make is an "emergency" section plainly visible (FAR 23.1581 b(2-i)) and easy for the pilot to turn to. Now, POH manuals are required to be bound in such a way they can be revised and amended (FAR 23.1581.(f)). The Cessna manuals made this change but the Diamond manual clearly is lacking this feature.

In conclusion: Diamond likely was either given a waiver, or was allowed to slip through the cracks based on the JAR-23 approval. This
does happen. In addition, for some reason the FAA did not require
Diamond to update deficiencies in their manual as they have done with other manufactures, and only the FAA knows
why.

What will eventually happen is Diamond will get sued and they will either update the manuals or declare bankruptcy and reform under a new legal entity. (like Marvel-Schebler/Bendix/Precision Aeromotive)

Great information guys appreciate it, for example I fly a PC-12 and in its performance charts it has a ASD but no AGD. We still brief our take off in a event of a engine failure like you should  but I’m learning that theirs more to AGD besides clearing a 35 Ft obstacle end of runway at V2. I was maybe thinking a FAR for 121/135 requirement. Makes a lot of sense that they have to include it in the POH for legality purposes but don’t you think they should have tht information for you any ways. The FAA does say some multi engine airplanes don’t have a AGD wondering why so when it’s so critical.

It depends on the aircraft in question.  This isn’t required for the certification of a light twin and is solely up to the OEM’s discretion to publish said information.

My recollection is the FAA prohibits commercial operations out of airports that are shorter than the accelerate stop distance. I have never seen a twin manufacture that does not publish the data.

Try out Diamond.  They do not publish that data on the DA42 or the DA62 airplanes

@ Carlo Felicion - thanks, I did... and it prompted me to answer :)

FAR 23.1585 f(2) and FAR 23.1587 d(5) require the POH manual to have accelerate-stop data.

The regulations are phrase that the OEM must provide “procedures and speeds for accelerate-stop distances”, not the publication of charts and accelerate stop distances.  Also the requirement for the  publication of accelerate-stop distances only apply to commuter-category airplanes under 23.1587.   Little different in the eyes of the law.


text:
What is an approved weather source for flying an instrument approach into an airport with no working ATIS?
What can you use as viable weather information landing at an airport with ATIS inoperative due to the tower being closed after hours? Let's assume the approach secondary weather source is also unavailable but the ADS-B weather information is current.
My real question is: can you use ADS-B weather legally in this situation to shoot an approach if needed?

If flying under Part 91 you don't need any reported weather minimums to attempt an approach, and if you can see the runway environment at the DA / MAP then you can land. However, the gotcha may be the altimeter setting, which you do need in order to know where the DA / MDA is.  I don't know whether it's permissible to use the FIS-B weather for the field as the source of the altimeter setting. I would be surprised that the weather data could make it to the FIS-B stream without also being available to ATC. Sometimes using a nearby airport's altimeter setting is allowed, with increased mins.

Are you asking about US regulations, or some other country's?

I edited your question to - hopefully! - make it clearer. If I got something wrong don't hesitate to edit again or roll back. Having said that, if there's no working weather source at the airport then where is the ADS-B data coming from? And although you asked about ATIS, this scenario is probably more likely to occur at a non-towered airport with ASOS/AWOS.

Use proper names please. Its FIS weather. ADS-B is not the only way to get it.

How is the ADS-b weather derived? If the ATIS is inop, it will usually be because the sensor equipment is inop. If that is the case, how would ADS-b get the data for that airfield? If the sensors are working and the transmitter is inop, you would get the weather directly from ATC. If you were in IMC and/or IFR, your Approach plate would list an alternate source of weather info, and/or minimums adjustments when the weather is not available.
Saying that, having the weather is not a requirement to land at a Class G or E airport in VMC. Most airports will revert to one of these when the tower closes. A pressure sensitive altimeter is not necessary in VMC. Title 14 CFR, Part 91.205(b) just says “Altimeter”.
In all other cases, follow the regs below:

91.121 Altimeter settings
  (a) Each person operating an aircraft shall maintain the cruising altitude or flight level of that aircraft, as the case may be, by reference to an altimeter that is set, when operating—
  (1) Below 18,000 feet MSL, to—
  (i) The current reported altimeter setting of a station along the route and within 100 nautical miles of the aircraft;
  (ii) If there is no station within the area prescribed in paragraph (a)(1)(i) of this section, the current reported altimeter setting of an appropriate available station; or
  (iii) In the case of an aircraft not equipped with a radio, the elevation of the departure airport or an appropriate altimeter setting available before departure; or.
  (2) At or above 18,000 feet MSL, to 29.92” Hg.

205(b) applies to VFR, not VMC. 205(d) is for IFR so it would apply to an aircraft shooting an approach, whether in VMC or IMC.

@Pondlife - If the OP were flying VFR, shooting a visual approach or canceled their flight plan prior to shooting the approach, 205(b) would apply. Clearance would not even be possible in Class G. You are right if the OP remains IFR, though.

Yes, the word "approach" can be a bit fuzzy for sure. Having said that, a "visual approach" is still an IFR procedure.

Thank you for the response, I had ATC have them read the weather at the destination to have it on tape and it they read the exact same thing that I read on the ADS-B. So is ADS-B going to be a substitute for ATIS / radio broadcast AWOS/ASOS?


text:
What are the main differences between scimitar and regular propellers?
I am looking to know the main differences between scimitar and regular propellers. Can somebody help me on this?

Closely related

If you're talking about a scimitar on a Cirrus or Bonanza there is little if any benefit other than just looking cool.  The turboprop market typically doesn't rely on "cool" as a marketing technique (it helps though) so there must be some advantage for high powered aircraft.  High powered in this case means C130 or A400.  I would also like a technical description.  Maybe Peter K will be along soon with a good answer.

The scimitar's swept back design results in less drag. On top of that it lets you increase the overall length of the propeller's airfoil without lengthening the diameter of the propeller. And since lengthening the propeller's diameter results in the tip of the blade traveling at a higher mach, the scimitar gives you all the benefits of a longer airfoil with none of the noise or drag penalties associated with a transonic propeller tip.

Welcome to the site! You may be right, but can you give some more detailed explanation and maybe some links? It would be great to know why a scimitar prop would have less drag.

Um, sorry? That was about as much as an explanation as Carlo gave so I just followed suit.

Primarily the curved sweep of the blade's leading edge, allowing for better efficiency at higher engine speeds.

If I remember correctly, doesn't the sweep of the blade allow it to turn faster because it keeps the tips from going supersonic at the higher rotation?

authors: ΕΛΕΝΗ ΣΤΑΦΥΛΑΡΑΚΗ